Criminal Minds: Meet the New BAU Boss — What's His History with JJ?

The BAU will get a new boss on Wednesday's Criminal Minds, but he's an old, familiar face to one person.

Unbeknownst to the rest of the team, JJ (A.J. Cook) has a history with newly instated section chief Mateo "Matt" Cruz (Esai Morales), with whom she worked at the State Department during her year away from the BAU. But don't think she recommended him for the vacated position (RIP Strauss!).

"She is completely shocked he's there. She is flipping out!" Morales tells TVGuide.com. "It's kind of funny. He plays it cool, but she doesn't know how to react. She definitely was not expecting to see him walk through the door, that's for sure."

It's especially shocking because Cruz arrives to the BAU on Wednesday's episode (9/8c, CBS) just hours after he and JJ have a not exactly covert run and breakfast together. The pair worked on a case together in the State Department — one that is so highly sensitive that no one else can know about it, let alone the fact that they know each other.

"That's why she's surprised. She thought they wouldn't or couldn't work together again and now here he is," Morales says. "But he tells her that he got assigned to the job. He himself doesn't know if it's his boss who did it or if it's a coincidence. Stranger things have happened where you talk to someone and go, 'You know, I was thinking about calling you.' Is this what's going on? Or is he lying to her?"

That kind of ambiguity is what Morales is hoping to convey with Cruz. Though one might assume his character is on the side of our heroes, the actor, who says he's been told "most" of JJ and Cruz's backstory, wants to play Cruz close to the vest enough to make fans — and his pals — second-guess. "I have friends who ask me, 'Are you a good guy or a bad guy? Are you an unsub?'" he says. "What I tell them is, 'I'm not going to tell you. I don't want to ruin anything for you.' I could be. Once you start doing your character, you run the risk of ruining the surprises that may or may not be in store."

What will be clear after his debut though is that Cruz is nothing like Strauss (Jayne Atkinson), whose overbearing ways irked the BAU early on — and let's not forget how she tried to use Prentiss (Paget Brewster) to oust Hotch (Thomas Gibson). Cruz, whom Morales describes as a "chameleon," will head out into the field with the team on their first case together, which will be enlightening for both parties.

"Who wants their boss in their sh--?" Morales says with a laugh. "Morgan [Shemar Moore] keeps his distance from him. And obviously JJ does for different reasons. Here's my thing. Give me a shot and maybe it'll be better. He has admiration for them, but he doesn't really understand what the big deal is until he gets there. By the end of his first episode, he has a great appreciation for Hotch & Co. and vice versa. I think Cruz is the kind of leader that knows people need to be left alone to do their best. But I also have to remind them that they do have a hierarchy to respond to. They're not an island unto themselves. They have to answer to their boss, but their boss doesn't have to be abusive or preachy with his authority."

But nothing Cruz does on the first day will assuage JJ's anxiety about his presence. And since this is the Behavioral Analysis Unit, the rest of the team will start getting suspicious as to the true nature of their relationship. As previously reported, all will be revealed in the 200th episode when a current case ties into Cruz and JJ's old one. But until then, Morales is happy to let fans' imaginations run wild — and that includes the affair theory that executive producer Erica Messer has already debunked.

"Let people think they're having an affair! I think that's more interesting, don't you think? Does he have feelings for her beyond the professional realm? I'm sure he has. But has he acted on it? That's the question," Morales says. "Ultimately, the story is very deep, very personal. It's something I wouldn't discuss about myself if I were involved and it's profound. They're special to each other."